The present invention relates to a method of forming various function of layers having high quality, a product with the layer, an optical film with the layer which is an anti-reflection layer, a dielectric coated electrode suitable for forming the layer, and a plasma discharge apparatus comprising the dielectric coated electrode, and particularly to a method of forming a layer on a substrate comprising generating a reactive gas in a plasma state at atmospheric pressure or approximately atmospheric pressure and exposing the substrate to the reactive gas in a plasma state to form a layer on the substrate, a product with the layer, an optical film, a dielectric coated electrode, and a plasma discharge apparatus.
Many materials in which a layer with high function is provided on a substrate are used in various kinds of products, for example, an LSI, a semi-conductor, a displaying device, a magnetic recording device, light to electricity conversion device, a Josephson device, a solar battery, and a light heat conversion device. Examples of the layer with high function include an electrode layer, a dielectric protective layer, a semi-conductor layer, a transparent electro-conductive layer, an electrochromic layer, a fluorescent layer, a superconduction layer, a dielectric layer, a solar battery layer, an anti-reflection layer, an anti-abrasion layer, an optical interference layer, a reflection layer, an anti-static layer, an electroconductive layer, an anti-stain layer, a hard coat layer, a subbing layer, a barrier layer, an electromagnetic radiation shielding layer, an infrared ray shielding layer, a UV absorption layer, a lubricant layer, a shape-memory layer, a magnetic recording layer, a light emission element layer, a layer applied to organisms, an anti-corrosion layer, a catalyst layer, a gas-sensor layer, and a layer for decoration. These layers with high function are formed according to a wet coating method such as a solution coating method or according to a dry coating method employing vacuum processing such as a spattering method, a vacuum evaporation method or an ion plating method.
The solution coating method is advantageous in high productivity, but is not necessarily suitable for formation of a layer with high function, since it is necessary to dissolve or disperse materials constituting the layer in a solvent to prepare a coating solution, and when the coating solution is coated on a substrate to form a layer, the solvent used remains in the resulting layer or it is difficult to obtain a layer with a uniform thickness. The solution coating method further has problem in that at the drying process after coating, the solvent evaporated from the coating solution pollutes environment.
On the other hand, the dry coating method employing vacuum processing can provide a layer with high precision and is preferable in forming a layer with high function. However, the dry coating method, when a substrate to be processed is of large size, requires a large-scale vacuum processing apparatus, which is too expensive and time-consuming for evacuation, resulting in disadvantage of lowering of productivity. As a method for overcoming the demerits in that the solution coating method is difficult to provide a layer with high function or use of a vacuum processing apparatus results in lowering of productivity, a method is described in Japanese Patent O.P.I. Publication Nos. 11-133205, 2000-185362, 11-61406, 2000-147209, and 2000-121804, which comprises subjecting a reactive gas to discharge treatment at atmospheric pressure or approximately atmospheric pressure, exciting the reactive gas to a plasma state and forming a layer on a substrate (hereinafter referred to also as an atmospheric pressure plasma method). The atmospheric pressure plasma method disclosed in these publications generates discharge plasma between two opposed electrodes by applying pulsed electric field with a frequency of from 0.5 to 100 kHz and with a strength of electric field of from 1 to 100 V/cm. However, although a layer with high function can be formed in only a small area according to the atmospheric pressure plasma method disclosed in the aforementioned publications, it is difficult to form a uniform layer over a large area. Further, it has been proved that the layer formed does not sufficiently satisfy performance to be required for a layer with high function. Accordingly, a means for solving these problems occurring in the layer formation as described above has been required.
The present invention has been made in view of the above. An object of the invention is to provide a method of uniformly forming a layer with high function over a large area with high productivity and with high production efficiency, a product comprising the layer, and an optical film comprising the layer, and to provide a dielectric coated electrode and a plasma discharge apparatus for carrying out the method and obtaining the product and the optical film.
The above object of the invention can be attained by each of the following constitutions:
(1) A layer forming method comprising the steps of supplying power of not less than 1 W/cm2 at a high frequency voltage exceeding 100 kHz across a gap between opposed electrodes at atmospheric pressure or at approximately atmospheric pressure to induce a discharge, generating a reactive gas in a plasma state by the charge, and exposing a substrate to the reactive gas in a plasma state to form a layer on the substrate.
(2) The layer forming method as described in item (1), wherein the total power supplied to the electrode exceeds 15 kW.
(3) The layer forming method as described in item (1) or (2), wherein the high frequency voltage has a continuous sine-shaped wave.
(4) The layer forming method as described in any one of items (1) through (3), wherein the substrate is relatively transported to at least one of the electrodes, whereby the layer is formed on the substrate.
(5) The layer forming method as described in any one of items (1) through (4), wherein the substrate is placed between the electrodes, and the reactive gas is introduced to the gap between the electrodes, whereby the layer is formed on the substrate.
(6) The layer forming method as described in item (4) or (5), wherein the length in the transverse direction of a discharge surface of the electrodes is equal to or greater than that in transverse direction of the substrate on which a layer is to be formed, the transverse direction being perpendicular to the transport direction.
(7) The layer forming method as described in item (6), wherein the length in the transport direction of a discharge surface of the electrode is not less than one tenth the length in the transverse direction of a discharge surface of the electrode.
(8) The layer forming method as described in item (7), wherein the discharge surface area of the electrode is not less than 1000 cm2.
(9) The layer forming method as described in any one of items (1) through (8), wherein at least one on one side of the electrodes is a dielectric coated electrode whose discharge surface is coated with a dielectric to form a dielectric layer.
(10) The layer forming method as described in item (9), wherein the dielectric layer is one formed by thermally spraying ceramic to form a ceramic layer and sealing the ceramic layer with an inorganic compound.
(11) The layer forming method as described in item (10), wherein the ceramic is alumina.
(12) The layer forming method as described in item (10) or (11), wherein the inorganic compound for the sealing is hardened by a sol-gel reaction.
(13) The layer forming method as described in item (12), wherein the sol-gel reaction is accelerated by energy treatment.
(14) The layer forming method as described in item (13), wherein the energy treatment is heat treatment at not more than 200xc2x0 C. or UV irradiation treatment.
(15) The layer forming method as described in any one of items (12) through (14), wherein the inorganic compound for the sealing after the sol-gel reaction contains not less than 60 mol % of SiOx.
(16) The layer forming method as described in any one of items (9) through (15), wherein the dielectric layer has a void volume of not more than 10% by volume.
(17) The layer forming method as described in item (16), wherein the dielectric layer has a void volume of not more than 8% by volume.
(18) The layer forming method as described in any one of items (9) through (17), wherein the dielectric coated electrode has a heat resistant temperature of not less than 100xc2x0 C.
(19) The layer forming method as described in any one of items (9) through (18), wherein the dielectric coated electrode has the dielectric layer on a conductive base material, and the difference in a linear thermal expansion coefficient between the conductive base material and the dielectric is not more than 10xc3x9710xe2x88x926/xc2x0 C.
(20) The layer forming method as described in any one of items (9) through (19), wherein the dielectric has a dielectric constant of from 6 to 45.
(21) The layer forming method as described in any one of items (1) through (20), wherein at least one electrode on one side of the electrodes has a cooling means comprising a path for chilled water in the interior, the at least one electrode being cooled by supplying chilled water to the path.
(22) The layer forming method as described in any one of items (1) through (21), wherein the substrate is a long-length film, at least one electrode on one side of the opposed electrodes is a roll electrode, which contacts the film and is rotated in the transport direction of the film, and the other electrode being opposed to the roll electrode is an electrode group comprising plural electrodes.
(23) The layer forming method as described in item (22), wherein each of the plural electrodes is prismatic.
(24) The layer forming method as described in item (22) or (23), wherein the surface on the side contacting the substrate of the roll electrode is subjected to polishing treatment.
(25) The layer forming method as described in item (24), wherein the surface on the side contacting the substrate of the roll electrode has a surface roughness Rmax of not more than 10 xcexcm.
(26) The layer forming method as described in any one of items (22) through (25), wherein air, which is introduced to the gap between the opposed electrodes together with the long-length film transported to the gap, is less than 1% by volume.
(27) The layer forming method as described in any one of items (22) through (26), wherein at least one power source is coupled between the one roll electrode and the electrode group, and the power source is capable of supplying a total power of not less than 15 kW.
(28) The layer forming method as described in any one of items (1) through (27), wherein a mixed gas containing an inert gas and the reactive gas is introduced to a gap between the electrodes and the mixed gas contains 90 to 99.9% by volume of the inert gas.
(29) The layer forming method as described in item (28), wherein the mixed gas contains not less than 90% by volume of an argon gas.
(30) The layer forming method as described in item (28) or (29), wherein the mixed gas contains 0.01 to 5% by volume of a component selected from oxygen, ozone, hydrogen peroxide, carbon dioxide, carbon monoxide, hydrogen and nitrogen.
(31) The layer forming method as described in any one of items (1) through (30), wherein the reactive gas contains a component selected from an organometallic compound and an organic compound.
(32) The layer forming method as described in item (31), wherein the organometallic compound comprises a metal selected from Li, Be, B, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Y, Zr, Nb, Mo, Cd, In, Ir, Sn, Sb, Cs, Ba, La, Hf, Ta, W, Tl, Bi, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.
(33) The layer forming method as described in item (32), wherein the organometallic compound is one selected from a metal alkoxide, an alkylated metal, and a metal complex.
(34) The layer forming method as described in any one of items (1) through (33), wherein the layer contains a compound selected from a metal, a metal oxide, a metal nitride, a metal carbide, and a metal boride.
(35) The layer forming method as described in item (34), wherein the layer contains a compound selected from a metal, a metal oxide, a metal nitride, and a metal boride.
(36) The layer forming method as described in item (35), wherein the layer contains a metal oxide.
(37) The layer forming method as described in item (35) or (36), wherein the layer has a carbon content of from 0.1 to 5% by weight.
(38) The layer forming method as described in item (37), wherein the layer has a carbon content of from 0.2 to 5% by weight.
(39) The layer forming method as described in item (38), wherein the layer has a carbon content of from 0.3 to 3% by weight.
(40) The layer forming method as described in any one of items (1) through (39), wherein the layer has a thickness of from 0.1 to 1000 nm.
(41) The layer forming method as described in any one of items (1) through (40), wherein the layer is one selected from an electrode layer, a dielectric protective layer, a semi-conductor layer, a transparent electro-conductive layer, an electro-chromic layer, a fluorescent layer, a superconduction layer, a dielectric layer, a solar battery layer, an anti-reflection layer, an anti-abrasion layer, an optical interference layer, a reflection layer, an anti-static layer, an electroconductive layer, an anti-stain layer, a hard coat layer, a subbing layer, a barrier layer, an electromagnetic radiation shielding layer, an infrared ray shielding layer, a UV absorption layer, a lubricant layer, a shape-memory layer, a magnetic recording layer, a light emission element layer, a layer applied to organisms, an anti-corrosion layer, a catalyst layer, a gas-sensor layer, and a layer for decoration.
(42) The layer forming method as described in item (41), wherein the layer is an anti-reflection layer.
(43) The layer forming method as described in item (20), wherein the substrate contains cellulose ester as a material.
(44) A product having on a substrate a layer formed according to the layer forming method as described in any one of items (1) through (43).
(45) The product as described in item (44), which is an optical film having an anti-reflection layer.
(46) The product as described in item (45), wherein the anti-reflection layer comprises a high refractive index layer with a refractive index of 1.6 to 2.4 containing titanium oxide as a main component and a low refractive index layer with a refractive index of 1.3 to 1.5 containing silicon oxide as a main component.
(47) The product as described in item (46), wherein the refractive index of the high refractive index layer is not less than 2.2.
(48) A product having on a substrate a layer containing a metal oxide as a main component, wherein the metal oxide layer has a carbon content of from 0.1 to 5% by weight.
(49) The product as described in item (48), wherein the metal oxide layer has a carbon content of from 0.2 to 5% by weight.
(50) The product as described in item (49), wherein the metal oxide layer has a carbon content of from 0.3 to 3% by weight.
(51) The product as described in any one of items (48) through (50), wherein the metal oxide is titanium oxide.
(52) The product as described in item (51), wherein the layer containing titanium oxide as a main component has a refractive index of not less than 2.2.
(53) The product as described in any one of items (48) through (52), wherein the metal oxide is silicon oxide.
(54) An optical film having on a substrate an anti-reflection layer, wherein the anti-reflection layer comprises a high refractive index layer with a refractive index of not less than 2.2, and the high refractive index layer contains titanium oxide as a main component and has a carbon content of from 0.1 to 5% by weight.
(55) The optical film as described in item (54), wherein the high refractive index layer has a carbon content of from 0.2 to 5% by weight.
(56) The optical film as described in item (55), wherein the high refractive index layer has a carbon content of from 0.3 to 3% by weight.
(57) The optical film as described in any one of items (54) through (56), wherein the anti-reflection layer further comprises a low refractive index layer with a refractive index of from 1.3 to 1.5 containing silicon oxide as a main component.
(58) The optical film as described in any one of items (54) through (57), wherein the substrate contains cellulose ester.
(59) The optical film as described in item (58), wherein the substrate contains a plasticizer.
(60) The optical film as described in item (58) or (59), wherein the substrate has a clear hard coat layer or an anti-glare layer on its surface.
(61) A dielectric coated electrode, in which a conductive base material is coated with a dielectric to form a dielectric layer, wherein the dielectric layer has a void volume of not more than 10% by volume.
(62) The dielectric coated electrode as described in item (61), in which a conductive base material is coated with a dielectric to form a dielectric layer, wherein the dielectric layer has a void volume of not more than 8% by volume.
(63) The dielectric coated electrode as described in item (61) or (62), wherein the electrode has a heat resistant temperature of not less than 100xc2x0 C.
(64) The dielectric coated electrode as described in any one of items (61) through (63), wherein the difference in a linear thermal expansion coefficient between the conductive base material and the dielectric layer in the dielectric coated electrode is not more than 10xc3x9710xe2x88x926/xc2x0 C.
(65) The dielectric coated electrode as described in any one of items (61) through (64), wherein the dielectric layer has a thickness of from 0.5 to 2 mm.
(66) The dielectric coated electrode as described in any one of items (61) through (65), wherein the dielectric is an inorganic compound having a dielectric constant of from 6 to 45.
(67) The dielectric coated electrode as described in any one of items (61) through (66), wherein the dielectric layer is one formed by thermally spraying ceramic on the conductive base material to form a ceramic layer, and sealing the ceramic layer with an inorganic compound.
(68) The dielectric coated electrode as described in item (67) wherein the ceramic comprises alumina as a main component.
(69) The dielectric coated electrode as described in item (67) or (68), wherein the inorganic compound for the sealing is hardened by a sol-gel reaction.
(70) The dielectric coated electrode as described in item (69), wherein the sol-gel reaction is accelerated by energy treatment.
(71) The dielectric coated electrode as described in item (70), wherein the energy treatment is heat treatment at not more than 200xc2x0 C. or UV radiation treatment.
(72) The dielectric coated electrode as described in any one of items (69) through (71), wherein the inorganic compound for the sealing after the sol-gel reaction contains not less than 60 mol % of SiOx.
(73) The dielectric coated electrode as described in any one of items (61) through (72), wherein the surface of the dielectric layer is surface finished by polishing treatment.
(74) The dielectric coated electrode as described in item (73), wherein the surface of the dielectric layer has a surface roughness Rmax of not more than 10 xcexcm.
(75) The dielectric coated electrode as described in any one of items (61) through (74), wherein the electrode has a cooling means comprising a path for chilled water in the interior of the conductive base material, the electrode being cooled by supplying chilled water to the path.
(76) The dielectric coated electrode as described in any one of items (61) through (75), wherein the electrode is prismatic.
(77) A plasma discharge apparatus providing a substrate at a gap between opposed electrodes, applying voltage across the gap at atmospheric pressure or approximately atmospheric pressure to induce a discharge, generating a reactive gas in a plasma state by the charge, and then exposing the substrate to the reactive gas in a plasma state to form a layer on the substrate, wherein the electrode on at least one side of the opposed electrodes is the dielectric coated electrode as described in any one of items (61) through (76).
(78) The plasma discharge apparatus as described in item (77), wherein the substrate is a long-length film, the electrode on at least one side of the opposed electrodes is one roll electrode, which contacts the long-length film and is rotated in the transport direction of the long-length film, and the other electrode opposed to the one roll electrode is an electrode group comprising two or more of the dielectric coated electrode.
(79) The plasma discharge apparatus as described in item (78), wherein the roll electrode is the dielectric coated electrode.
(80) The plasma discharge apparatus as described in item (78) or (79), wherein the surface contacting the film of the roll electrode has a surface roughness Rmax of not more than 10 xcexcm.
(81) The plasma discharge apparatus as described in any one of items (77) through (80), wherein the discharge surface area of the electrode is not less than 1000 cm2.
(82) The plasma discharge apparatus as described in any one of items (77) through (81), wherein the length of the electrode is greater than that of the substrate.
(83) The plasma discharge apparatus as described in any one of items (77) through (81), wherein at least one power source is coupled between the one roll electrode and the electrode group, and the power source is capable of supplying a total power of not less than 15 kW.
(84) A plasma discharge apparatus providing a substrate at a gap between opposed electrodes, applying voltage across the gap at atmospheric pressure or approximately atmospheric pressure to induce a discharge, generating a reactive gas in a plasma state by the charge, and then exposing the substrate to the reactive gas in a plasma state to form a layer on the substrate, wherein the substrate is a long-length film, the electrode on at least one side of the opposed electrodes is a roll electrode, which contacts the long-length film and is rotated in the transport direction of the long-length film, the other electrode opposed to the roll electrode is a dielectric coated electrode, in which a dielectric is coated on a conductive base material to form a dielectric layer, and the surface contacting the film of the roll electrode has a surface roughness Rmax of not more than 10 xcexcm.
(85) The plasma discharge apparatus as described in item (84), wherein the surface contacting the film of the roll electrode is subjected to polishing treatment.
(86) A plasma discharge apparatus comprising the dielectric coated electrode as described in any one of items (61) through (76).